Musnad Ahmad 31:406

Ishaq ibn Isa narrated to us, Abd al-Rahman ibn Zayd narrated to us, from his father, from Ata ibn Yasar, from Abu Sa’id al-Khudri, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "The Suhoor is a blessed meal, so do not abandon it, even if one of you were to take a gulp of water, for Allah and His angels send blessings upon those who eat the Suhoor."